For those interested, I believe I've discovered the cause of the early Model S windshield cracks, and the design change that was implemented to fix it. Early Model S windshields had a taper/chamfer on the edges. Instead of being squared off, the glass thinned out at the edges. I presume this was for aerodynamic reasons, but might also have been for ease of manufacturing. Anyway, this tapering essentially meant that the edge of the windshield glass was experiencing more stress than other parts of the glass. Since the edges experienced more stress, cracks would initiate on the edges and start propagating inward. After my windshield was replaced about 45 days ago, I realized that this taper is no longer in the edge of the glass. It does not have a chamfer at the edges. Thicker edges = less stress on the glass. Just an observation.